With a view to form an ultrafine copper wiring in a semiconductor device, there is proposed a method of forming a barrier film composed of a manganese silicate (MnSiO3 or Mn2SiO4) film by a chemical vapor deposition (hereinafter referred to as CVD) method. In this method, a manganese metal film is formed by depositing a manganese metal on a silicon-containing oxide film formed on a substrate using a manganese precursor. Then, the substrate having the manganese metal film formed thereon is annealed for five minutes at a temperature of 300 to 400 degrees C. under an atmosphere added with a small amount of oxygen. Thus, the manganese metal becomes a silicate by reacting with silicon and oxygen of the underlying silicon-containing oxide film, whereby a manganese silicate film is formed.
In this method, the annealing is performed after forming a copper film on a manganese metal film.
However, it was found that, even if a manganese metal film is formed by depositing a manganese metal on a silicon-containing oxide film as an underlying layer through the use of a CVD method, an interfacial layer composed of a manganese silicate may sometimes not formed in an interface with the silicon-containing oxide film. Even though the interfacial layer is formed, it is unclear in the CVD method what kind of parameter decides the existence or absence of the interfacial layer composed of a manganese silicate. Furthermore, a barrier film composed of a manganese silicate film cannot be said to have sufficiently high adhesion to an upper-layer metal film (e.g., a copper film).
Moreover, the thickness of a barrier film affects a barrier property. From the viewpoint of avoiding the reduction of a cross-sectional area of a groove or a via-hole buried with a metal wiring, it is required to make the barrier film thinner. In the CVD method, it is unclear what kind of parameter decides the thickness of the interfacial layer.